Work stop for use with collets



May 3, 1949- l.. R. EVANS 2,469,160

WORK sfvvToP FOR USE WITH coLLETsv v Filed sept. 12, '1947 v 2sneets-slwewl 27 3f@ fd 32.

IN VEN TOR.

l L. R. EVANS WORK STOP FOR USE WITH. COLLETS May 3, 1949.

2 Sheets-Sheet 2 Filed Sept. 12, 1947 INVENTOR.

BMW@ (Y, cornysl.

Patented May 3, 1949 UNITED STATES PATENT oFFlcE WORK STOP FOR USE WITHCOLLETS Leigh R. Evans, Elmira, N. Y., assignor to Hardinge Brothers,Inc., Elmira, N. Y.

Application September 12, 1947, Serial No. 773,542

12 Claims. l

This invention relates to improvements in work stops for use on lathesand other machines employing collets for holding the work.

Work stops have been mounted on collets or chucks in such a manner as tobe movable therewith and such work stops may have the desired degree ofaccuracy when the Work is of uniform diameter. Commercial rods and bars,however, vary considerably in diameter and if the work to be clamped inthe collet is, for example, several thousandths of an inch under size,the collet must be drawn into the lathe spindle to a greater extent,thus drawing the stop inwardly from the work supporting end of thespindle to a similar extent. If the Work is several thousandths of aninch over size, the collet will not be drawn into the lathe spindle tothe same extent as when the collet is operating on work of the correctdiameter, and consequently, the stop will also be nearer to the workreceiving end of the lathe spindle. Consequently, when a high degree ofaccuracy in the location of the stop is required and the work variesslightly in diameter, such stops secured to the collets themselvescannot be successfully used.

One of the objects of this invention is to provide a work stop forcollets employed in machines having rotary spindles and in which thestop will be accurately positioned with reference to the work holdingend of the machine spindle, regardless of variations in diameter of thework. Another object of this invention is to provide a work stop formachines of this type which is capable of operating with a much higherdegree of accuracy than collet stops heretofore commonly employed, andwhich is also positive and reliable in its action. Another object is toprovide a work stop which is arranged within the collet, and which hasmeans for gripping the lathe spindle to ensure accurate positioning ofthe work with reference to the spindle of the machine. A further objectis to provide a stop of this type which includes a plurality of spindlegripping parts which extend through the usual slots between the springngers of a collet, and which are pressed into engagement with the lathespindle by means extending into the collet. A further object is toprovide a work stop in a machine of this type in which the lockingmechanism is arranged` in close proximity to the work supporting end ofthe spindle to avoid inaccuracies due to the resilience of various partsof the stop. Another object is to provide work stop in which the lockingmechanism is arranged to cooperate with a -part of the tapered bore ofthe spindle so that the stop is secured in place by a Wedging action, aswell as by frictional engagement with the spindle. Other objects andadvantages of this invention will be apparent from the followingdescription and claims.

In the accompanying drawings:

Fig. 1 is a fragmentary elevation of the head stock of a lathe inconnection with which my improved stop is employed.

Fig. 2 is a fragmentary central sectional elevation thereof, on anenlarged scale, showing my improved stop in operative relation to acollet and a spindle.

Fig. 3 is a fragmentary transverse section thereof, on line 3-3 of Fig.2.

Fig. 4 is an elevation of a collet having my improved stop means appliedthereto,

Fig. 5 is a central sectional elevation, taken partly on line 5 5, Fig.4, with the collet omitted, and showing the stop mechanism separate fromthe collet.

Fig. 6 is an end elevation of the structure shown in Fig. 5.

Fig. 7 is a fragmentary sectional view, on line 1 1, Fig. 3.

Fig. 8 is a perspective view of one of the locking blades of the stopmechanism.

My improved stop mechanism may be applied to any machine having aspindle on which the workpieces may be supported, and in theaccompanying drawings, I have, by way of example, illustrated theinvention as applied to a lathe having a headstock I0 in which a spindleI I is rotatably mounted in any suitable manner. The work supporting endof the spindle, as shown in Fig. 2, has an internal frusto-conical boreI2 which extends from the end of the spindle to a .slightly taperingbore I4. Both of these bores are formed for cooperation with a collet I5having the usual spring fingers terminating at their outer ends in workgripping jaws I6 having substantially frusto-conical or tapered outersurfaces Il formed to cooperate with the tapered bore I2 of the lathespindle. The bore I4 which has less taper than the bore I2 permits thespring fingers to move outwardly when the collet is moved into releasingposition, i. e., to the right in Fig. 2. The spring :lingers are spacedfrom each other by means of the usual slots I8. The collet may beprovided with a keyway IS into which a key member 20 in the spindle IImay enter to cause the collet to turn with the spindle. A collet of anyother suitable type may be provided. 2| represents a collet draw bar ortube to which the inner end of the collet is secured, for example, by

means of a threaded engagement with the inner end of the collet. Thisdraw bar or tube may be actuated to move the collet into and out of Workengaging positions through its knob or handwheel 22. All of the partsthus far described have heretofore been used in connection with lathesand other machines, and of themselves, do not constitute apart ofthisinvention.

My improved Workl stop includes a Work engaging member Which may be ofany suitable or desired form, that shown being in the form of avthreaded rod or screw 25 adjustably mounted (on a draw bolt 21 whichforms apart of the" mecha-7 nism for locking the stop with relation tothe spindle of the machine. Y however, that the draw bolt itselftmay b eused as a Work stop to limit the extent t'ovvhich Work It win-'tonderste'Qd;

may be inserted into said collet. ln the particuy lar constructionillustrated, the draw bolt has an axially extending threaded hole inwhich the stop member 25 has a threaded engagement for adjustirg' thesainev lengthwise relatively to" the draw bolt, and 2,'8 represents'alocking screw'which may' be turned' into" engagement vviththefst'opmember or screw 25 to hold' the' stop screw sen curely in any', desired:position; n The drawk bolt 'provided'w'ith a cylindricalbo'dy portion.23 terminating at one e'n'd thereof in aj' screw-threaded part 36 andlhavingna enlarged head 3l' at the other end'thereof the head" having atapered or frusto'r-'conical portion 3'2 terminating at the y('ylndlcilportion' ZQW'' the' da'W bblt.

The lockingof the draw bolt arrdof' thevvork stop member 25V mountedthereon tothe spindle H may be effected in any" suitable manner bymeans' of lockingpartsl eitend outwardly through slotsg of the` c olletinto engagement' with the' bore" of the spindle, and if desired, the'slots of the'4 collet may' be" el'i'la'rg'edN as indicated at operateWith a sleeve 38iforn'1ed to slid-ingly over' the cylindricalsurface-[2am tile draw boit. This sleeve is provi'ded4 with radiallslots'terrn'inating' at one end thereof, the slots being formed toreceive the locking leaves 6 the other end of each" slot is" providedvvth a" taperingV race 39 formed to engagea tapering or inclined faceofy a locking leaf'l Consequently, it will be evident frominspectioh'jof Figs'. 2 and 5 that if the sleeve is moved to the right,the inclined face 39 thereof cooperating with the tapering face 3'2 oftbe locking b'olt vvill force thelc/clringv leaves 36 outwardly. 'lfledraw bolt aridJ the" sleeve,v conse quently, constitute cooperating?members which mayl be moved relativelyv to each other to move thelocking leaves". into engagement with the spindle. The adjustment of'the sleeve relatively to the locking bolt may be eil'c'tedVv in any suitajble` or desired manner, and inthe construction illustrated, a nut lllis provided vvliiclY engages the threaded' portion; 3G' of thelockingbolt. The draw bolt and sleeve 3'8'; consequently, actl as Wedges tomove the locking leaves against the spindle.

v'I 'he locking leavesA 36 are located mediate of the endsof thelcolletY and the outer surfaces thereof engage the slightly taperingp'rtion hl of the bore of the spindle and the cylindrical bere of thespindle at the inner end of the tapering portion I4, and consequently,the outer spindle engaging surfaces of the locking leaves 3&3 also haveportions 44 which are inclined with reference to the axis of the spindleso as to t snugly on the tapered surface M of the spindle and straightportions 4I which.itvag-ainstl the cylindrical portions of the spindle.This construction has the advantage that when the work stop is locked tothe lathe spindle, any impact of the Work against the stop member 25will not tend to slide the 1o`cking-l mechanism lengthwise of thespindle because of the Wedging action of the inclinedportions d4 of theleaves with reference to the slightly tapered bore I4 of the spindle.Any impactag'a'instithe stop member or the colletvn` the oppositedirection will be opposed by the straight portions 4I which bear againstthe cylindrical portion of the spindle. Consequently the stop Will' besecurelyv held onA the spindle against movement in' either" direction; l

ln order to prevent the: draw boltj from'turriing relatively to thesleeve', the draw bolty maybe provided with" a key or spline412:'for1ned to lavev a sliding t in the keyway' 43 of the sleeveu Y Itis desirable tofprvide means* for Holding the' lockingVV leaves" 36T inoperative' relation" tothe collet when the collet is removed from the"spindle. Any suitable means may be employed for this purpose,- andz inTthe' ccsivrstriictioriy (illustrated, I have providedI the sleeve3-tvitlf` undercut grooves or' recesses 5 adjoining the slotsi'ntovihiclf'the locking leaves extend; se' particularly: Figs. 3 and:7'.- Tlie' locking leaves`- pfrcvyvide'd;A nea'r t s eir inneredgeswitlj pro cti'onsll' adapted" t'o enter into the undercutStoasufcierit extent?r to preieiit the leaves'v from droppinglou't ofAthe slots in ther sleeve and the* colletl- These projections may befc'ri'i'edj i'ir' anyr suitable or desiredmanner, ad the'corist'rilotion1N illus:- trate'd I` have providedr tliej inner edges oVhe leaves with a pairv ofspacd sletU "T etending ersst'iise' off theleaves; lavi gf a'- o ue between the slots, and this ton" f over'in anysuitable manner't provide" tlie projections 48 on'A each leafl xte A"ngt'cnvari' one side thereof, WhichA enters int the' undercut groove 45off the sleeve 38 Wh the lea-f5 isA slid frito"V operative positionthrough tl'e1 openv end of its slot.y Any other means for holdingvthelocliin'g leaves againsty dislod'gement fromthe collet r'iiayb'eLvprovided. 'l'e'se projections. h'ovvever, t loosely in the undercutygrooves soas*v not to interfere withI the moving ofth leaves in'tofandout of engagen'ie'n'tv with the spindle, andA do not extend; laterallyof the4 leaves to a'.y Sulo'ieteirter-t to" prevent insertion of theleaves through the slots 35 of the collet. The projections4 Q'Gf alsoserve the further purpose of ensuring the as- S'mblyn'g of the leaves fl(ll'ectrelattri'` 'tv'le c'o'llet so that the taper at'tlie'rv outersurta es' of the leaves will correspond the i'l'ape'rl I'Ef in the'boreV of the spindle:

Itwill also be' noted that the length of the leaves 36 is materiallyless than tlielergth; of the niargeijents as of thel slots off theconst. oder sequently, after the Work' stop has be'enfloc'k'ed is. thespindle, as shown ifi Figs. i s, sy tightening the nut 4U', the colletis free to rnove lengthwise to the neessary' extent to grip theilforkpi'ece,` suchlv as 50; Fi 2, and to'v releaseit.

In the operationof nisrn, when: the sli-Sop c' tinted. in sindL reeks-d1te tri spinale* :fr

work stop member or screw 25 has been adjusted to the desired position,workpieces may be fed between the jaws of the collet into engagementwith the end of the stop member 25. As the collet is drawn to the leftin Fig. 2 to grip the work, the stop mechanism does not move because ofthe fact that it is locked to the spindle. Consequently, even if theworkpieces 5i! vary in diameter, they will still always be gripped bythe jaws of the collet in fixed relation to the end of the spindle. Bymeans of the construction illustrated, the positioning of the workpieceswill not vary more than a small fractionof av thousandth .of an inchduring the operation of the machine. The fact that the stop mechanismand the lock- ,E stop were located at a considerable distance from theWork receiving end of the spindle.

It will be understood that various changes in the details, materials,and arrangements of parts Whichfhave been herein described andillustrated Y in order to explain the nature of the-invention,

may be made by those skilled in the art within the principle and scopeof the invention, as expressed in the appended claims.

I claim as my invention:

1. In a work stop device for use with a machine having a rotary spindleand a collet extending into said spindle and having spring iingersspaced apart by slots, that improvement which comprises locking partsextending through said slots, and wedge means for forcing said lockingparts outwardly into engagement with that portion of said spindle whichextends about said collet, said locking parts being spaced from the endsof said slots to permit lengthwise movement of said collet relatively tosaid spindle and said locking parts.

2. .In a work stop device for use with a machine having a rotary spindleand a collet extending into said spindle and having spring ngers spacedapart by slots, that improvement which comprises locking parts extendingthrough said slots, a pair of relatively movable members having portionsengaging said locking parts to move the same outwardly into engagementwith said spindle, means for moving said movable members relatively toeach other to wedge said locking parts in engagement with said spindle,one of said members having a work stop associated therewith, saidlocking parts, when in their operative positions in a spindle beingspaced from the ends of said slots to permit movement of said colletinto and out of work gripping positions.

3. In a work stop device for use with a machine having a rotary spindleand a collet extending into said spindle and having spring fingersspaced apart by slots, that improvement which comprises locking part-sextending through said slots and having bevelled portions within saidcollet, a pair of members extending into said collet and having inclinedportions engaging said bevelled end portions of said locking parts, saidmembers being movable relatively to each other to force said lockingparts outwardly into gripping engagement with said spindle by engagementof said inclined portions with said bevelled portions, said slots ofsaid collet being longer than said locking parts to enable said colletto move lengthwise of said spindle when said locking parts are inlocking positions.

4. In a work stop device for use with a machine having a rotary spindleand a collet extending into said spindle and having spring ngers spacedapart by slots, that improvement which comprises locking parts extendingthrough said slots, a draw bolt in said collet, a sleeve on said drawbolt, cooperating wedge parts on said draw bolt and said sleeve forWedging said locking parts outwardly into engagement with said spindlewhen said sleeve and draw bolt are moved relatively to each other, and anut having a threaded engagement with said draw bolt for producingrelative motion of said draw bolt and said sleeve. v

5. In a work stop device for use with a machine having a rotary spindleand a collet extending into said spindle and having spring fingersspaced apart by slots, that improvement which comprises locking leavesextending through said slots of said collet and of less length than saidslots and having bevelled end portions Within saidr collet, a draw bolthaving a head provided with a substantially frusto-conical part formedto engage said bevelled portions of said leaves, a member extendingabout said draw bolt and movable relatively to the same and havingportions formed to engage said leaves, means for moving said membertoward the head of said draw bolt into engagement with said leaves forforcing said leaves outwardly into engagement with said spindle, saiddraw bolt having means thereon for engaging the work to limit the extentto which the same may be inserted into said collet.

6. In a work stop device for use with a machine having a rotary spindleand a collet extending into said spindle and having spring iingersspaced apart by slots, that improvement which comprises locking leavesextending through said slots of said collet and of less length than saidslots and having bevelled end portions within said collet, a draw bolthaving the head thereof arranged within said collet and shaped tocooperate with the bevelled end portion at one end of each of saidleaves, a sleeve extending about said draw bolt and formed to engage theother bevelled end portion of each of said leaves, and means for movingsaid sleeve relatively to said draw bolt in a direction to force saidleaves outwardly into engagement with said spindle, said draw bolthaving means thereon for engaging the work to limit the extent to whichthe same may be inserted into said collet.

'7. A work stop device according to claim 6 characterized in that saidsleeve is provided with longitudinal radially extending slotsterminating at one end thereof and into which the inner portions of saidleaves extend, the portion of said sleeve at the ends of said slotsbeing inclined to engage bevelled ends of said leaves for moving saidleaves outwardly when said sleeve is moved toward said head of said drawbolt.

8. In a work stop device for use with a machine having a rotary spindleand a collet extending into said spindle and having spring fingersspaced apart by slots, that improvement which comprises locking leavesextending through said slots of said collet and of less length than saidslots and having bevelled end portions within said collet, a draw bolthaving a head arranged within said collet, said head having asubstantially frustoconical face arranged to engage one bevelled end ofeach of said leaves, a sleeve slidably mounted on said bolt and havingslots extending inwardly from one end thereof into which said leaves mayenter, the end walls of said slots being inclined to 'vetwiid tiiieiheadof seid boit for l5 8 exten'dz when the millet:y is inworlc releasing:position, that improvement which comprises loe'king -parts extendingthnougm said@ slots of, salda c'olet into position to engagefsaidslightly taperingsfportion of said? sl'e'evfe;C me'ains within; said;coileiir for forcing: said locking parts outwardly imo engagement.withvsaid slightly' tapering; boreV of, said spindle, said lockingfparis`loeing spaced from' the ends of saidl slots to permit'f lengthwisemovement of said colifeii` relatively to'` said spindle and said lockingparte,L and a'. work stop afssociare'd with said means for limiting mevextent te which Work may be insert'edi'nt saidf collet.

12. A work' shoprdevice awardingto claim 11, i-'n which: ther parte arethe formof leaves having their @mier` face'sia/peifing t6 engage the'slightly tapering face of said spindle'.

REFERENCES (CITED The following references areu yof record inthe;

111e of this 4ifrererniz' UNITED STATES PATENTS

